in the same way as humans, biodiversity is just as important to the species of our planet as it is to us. When you add in the benefits that we reap from a diverse environment, it soon becomes apparent that maintaining a stable balance of healthy species and ecosystems is good for everyone.
From the perspective of the species themselves, having a wide range of associated species is important as they each rely on one another in order to survive. Every organism within a system has its own role and serves a vital function on a variety of levels, such as bees which act as pollinators for plants, certain species of mussels which use fish as their larval host, and simple predator/prey relationships such as between pike and red swamp crayfish¹,²,³. Remove any one of these species from the equation and the effects can be disastrous, in what is known as a trophic cascade⁴.
Take for example, the classic case of the sea otter⁵. As a predator, sea otters feed on sea urchins, keeping populations in check but when otter populations drop, the urchins proliferate. They then consume huge amounts of kelp, wiping out vast swathes and removing habitat and food for a myriad other species, leaving little more than an underwater desert and the threat of extinction.
Biodiversity is also key for the continued provision of ecosystems services it provides, which serve both humans and the systems themselves, although the term is largely used in relation to the benefits reaped by us⁶. The list of services is extensive and includes soil formation; nutrient storage; pollution breakdown; recovery from unpredictable events; the provision of biological resources such as medicine and food; and social benefits such as employment, research and recreation.
Diversity is important for species in order to maintain resilience against unexpected events, such as sudden climate changes or natural disasters, like forest fires or floods⁷. If a fire tears through a forest in which only one species of exists but which is wiped out by the fire, that forest is less likely to adapt to the loss of the reptile than one where 20 species exist. Although some ecosystems may be insensitive to species loss, due to variations in ecosystem types, the presence of multiple species which perform a similar role, their relative unimportance or because of other abiotic factors, it is clear that higher numbers of species are needed to ensure stable provision of services⁸.
Linked to the idea of resilience is that of genetic diversity, the variations within a species that allow them to adapt on an individual basis over time, as beneficial genes are passed through generations. A wider range of genetic diversity allows species to build resistances to diseases, as shown in studies on leaf-cutting ant colonies and fruit flies, and strengthens the possibility that at least some individuals will survive, and by making them less susceptible to inherited disorders⁹,¹⁰,¹¹.
In essence, any reduction of the diversity of life, whether by human hands or by natural causes, weakens the links that exist among species and habitats. Given the interconnected nature of ecosystems, where a change in one area can have far reaching effects elsewhere, it is therefore vital to maintain as great a variety of species as possible in order to ensure the continued healthy existence of the planet.